Cross-fired regenerative furnaces have been commonly employed to manufacture glass. A typical cross-fired regenerative furnace has a melting chamber in which glass forming ingredients such as silica, boric oxide and other additives including stabilizers and fluxes, are heated by air-fuel burners which are placed along the lateral sides of the melting chamber. By combusting fuel in the presence of preheated air from a regenerator, the air-fuel burners provide heat to the atmosphere and walls of the melting chamber, which, in turn, heat the glass forming ingredients in the melting chamber by convection and radiation. Although the thermal efficiency of this heating process is relatively high, the glass production rate may decrease with time because of decreasing regenerator performance and increasing wall losses. The performance of the regenerator, for example, may be deteriorated when the regenerator is partially plugged or partially destroyed due to the presence of chemical contaminants in the resulting combustion gases which pass through the regenerator.
An oxygen enrichment technique has been proposed for increasing the melting capacity of a cross-fired regenerative furnace. The technique involves introducing oxygen in an area of the furnace where a fuel is being combusted in the presence of air. This technique, however, has a number of disadvantages. First, the addition of oxygen has no concentrated effect on a specific area, such as the batchline or in the vicinity thereof, where a high temperature condition is needed to melt floating solid glass batch. The consumption of oxygen is, therefore, high for a low glass production increase. Second, the air flames, which are at a high temperature due to the presence of oxygen, radiate more heat to the roof of the melting chamber. When the roof is subject to such a condition for a long period, its useful life could be reduced.
The use of oxygen-fuel auxiliary burners in a number of glass making furnaces has also been proposed. For instance, oxygen-fuel auxiliary burners have been employed on the sides of a rectangular melting chamber of a conventional U-shape flame regenerator furnace to assist the melting process. However, oxygen-fuel auxiliary burners have not been employed successfully in a cross-fired regenerative furnace. The major factor which is hindering their use in a cross-fired regenerative furnace is the difficult and restricted access to the furnace melting space. This access normally consists of a small (1 m wide) corridor between the regenerators and the melting furnace, not allowing the conventional installation of oxygen-fuel auxiliary burners.
It is, therefore, an advantage of the present invention in installing oxygen-fuel auxiliary burners in a cross-fired regenerative furnace in such a manner to accommodate the restraints imposed by the regenerators.
It is another advantage of the invention in installing oxygen-fuel auxiliary burners in a cross-fired regenerative furnace without drilling any holes in the refractory lining of the furnace.
It is yet another advantage of the invention in maintaining a particular glass production rate even when the regenerators of the furnace are partially plugged or destroyed, or are being repaired.
It is an additional advantage of the invention in increasing the glass production rate without consuming excessive amounts of oxygen and fuel and without overheating the roof of the furnace.
It is a further advantage of the invention in being able to employ non water-cooled oxygen-fuel auxiliary burners.